được gọi là một Encryption Key (FEK), để mã hóa các tập tin. Các thuật toán mã hóa đối xứng được sử dụng bởi FEK phụ thuộc vào phiên bản của hệ điều hành của máy tính: Đối với Windows 2000, thuật toán mã hóa dữ liệu tiêu chuẩn XORed (DESX) được sử dụng để mã hóa các file. Đối với Windows XP không có gói dịch vụ, | 588 Part III Deploying Application-Specific Solutions 5. In the Change Security Settings dialog box click OK. 6. In the Trust Center dialog box click OK. Enabling S MIME in OWA To allow S MIME usage in OWA you must install the S MIME Microsoft ActiveX control at the client computer. The S MIME ActiveX control enables using S MIME for both signing and encrypting e-mail messages. Important Only a local administrator or member of the local Power Users group can install the ActiveX control. Once the control is installed all users can use it. In addition the ActiveX control requires Microsoft Internet Explorer Windows Internet Explorer or later running on Windows 2000 or later. To install the S MIME ActiveX control 1. Log on to the computer as a member of the local Administrators or Power Users group. 2. Open Internet Explorer. 3. In Internet Explorer open the URL http ExchangeServer exchange where ExchangeServer is the DNS name of the computer running Exchange Server 2003 hosting the user s mailbox . 4. When prompted type the user name and password for accessing your mailbox. 5. In Outlook Web Access in the Navigation Pane click Options. 6. On the Options page under E-Mail Security click Download. 7. In the File Download dialog box click Open. 8. If any security warnings appear click Yes to install the ActiveX control. Sending Secure E-Mail Once you have enabled S MIME in the e-mail package the decision to send secure e-mail is made for every message sent by the e-mail participant. For example Figure 22-6 shows a message window in Outlook 2007 that is enabled for both digital signing and e-mail encryption. By selecting the Digitally Sign button and the Encrypt button the sender can decide whether to implement signing encryption or both encryption and signing for the outbound e-mail message. In addition the user can select the defaults to enable within the e-mail client for S MIME e-mail. Chapter 22 Secure E-Mail 589 Figure 22-6 Enabling digital signing and .
